Parkinson's disease is an example of a progressive neurodegenerative disease. It is usually diagnosed in adulthood, usually when the patient is about 55 years of age, and is characterized by tremors, rigidity, and bradykinesia. It is well understood that many of the abnormalities found in these patients are due to the loss of dopamine (DA) neurons in the substantia nigra and the depletion of striatal dopamine levels. More recently, there has been a re-evaluation of the signs and symptoms found in Parkinson's disease patients that has led to the conclusion that Parkinson's disease is a systemic disease with involvement of peripheral nervous tissue. For example, the loss of the sense of smell has been found to be an early sign of Parkinson's disease reported in most patients. Often, the earliest sign of Parkinson's disease in patients is the loss of the sense of smell so that this symptom can be used as a diagnostic in patients with early disease. This symptom of disease is probably due to loss of neurons in the olfactory bulb of the brain. Also, orthostatic hypotension has been shown to be one of the more common signs of Parkinson's disease, probably due to a direct effect on the peripheral nervous system (PNS) of the host. Clinical manifestations of Parkinson's disease are not apparent until over 80% of the central or peripheral neurons have degenerated. Most new Parkinson's disease patients are started on dopamine (DA) agonists when first diagnosed, but usually progress to L-DOPA (L-dopamine), the precursor of dopamine in tissue. As a therapeutic, L-DOPA is used to relieve Parkinsonian motor signs, but has very little effect on PNS signs and symptoms of disease. In fact, its long-term use is usually associated with diminished efficacy and increasingly bothersome side effects. Other examples of chronic degenerative neurological disorders that might be treated in a similar manner include macular degeneration, urinary incontinence, Alzheimer's disease, Multiple Sclerosis, and short term memory deficiency. These disorders have in common three characteristics; they are usually diagnosed late in life, there is evidence of familial, but not Mendelian genetic inheritance of each disease, and patients will have had a period of time as adults before diagnosis of disease when the host appears to function normally without evidence of signs or symptoms of the chronic disease.
Over the past few years, tremendous strides have been made in understanding the crucial role that stem cells play in embryogenesis and organogenesis. Much of the accumulated data indicates that stem cells play an important role in the development and maturation of mammals. It is well known that each organ of the adult body contains progenitor stem cells that can respond to signals from other cells or injured tissue and migrate to the site of injury to help restore the tissue to normal health. In animal models, the “self-repair” system clearly responds to acute injury of tissues in the body and recruits stem cells from the bone marrow and other parts of the body to help with the repairs. Stem cells are also required to sustain those functional cell populations that turn over rapidly in the body such as skin and the various lymphocyte populations. The “self-repair” system is only now being demonstrated in human studies.
With the beginning of an understanding of the “self-repair” system and its probable role in response to tissue injury, researchers have proposed that delivering somatic progenitor stem cells directly to the site of damage might augment the hosts own “self-repair” system and more quickly and completely repair the damage to the host tissue. For example, neural stem cell lines have been successfully used to treat spinal cord injuries mice and rats. However, this “self-repair” response appears to be determined by a complex interaction between cells and protein mediators produced by host and donor cells. Understanding the factors involved and their roles in this response and the differentiated state of the cells involved will be crucial to devising methods for controlling and utilizing this system for providing new therapies for chronic diseases. Studies are ongoing in many laboratories to further define the factors and cells involved. Most recently, continuous infusion of Glial-Derived Neurotrophic Factor (GDNF), a stem cell growth factor, directly into the brain has been claimed to have benefit for patients with Parkinson's disease.
Over the past several years, significant interest has developed in using mobilized peripheral blood progenitor cells for allogeneic hematopoietic reconstitution. Treatment of stein cell donors with a five-day course of Granulocyte-Colony Stimulating Factor or its pegalated derivative causes the release of stem cells from the bone marrow into the circulating blood and greatly increases the number of hematopoietic and other stein cells that could be harvested from the donor. This procedure requires Granulocyte-Colony Stimulating Factor be administered to otherwise normal donors in order to release stem cells into the peripheral blood where they can be collected by leukophoresis and prepared for transplantation. Many studies have reported the use of Granulocyte-Colony Stimulating Factor in normal volunteers and normal donors, usually at a dose of 5 to 10 micrograms per kg per day for 4 to 8 days. The most common side effect was bone pain. While the toxicities were frequent, the severity was generally mild and very few normal donors had to discontinue Granulocyte-Colony Stimulating Factor because of the side effects. Persons treated with Granulocyte-Colony Stimulating Factor were found to have a surge in peripheral blood stem cells 4 to 7 days after initial treatment. The use of Granulocyte-Colony Stimulating Factor for mobilizing peripheral blood stem cells is widespread and appears to be safe and to be capable of generating the stem cells needed for allogenic or autologous transplantation.
Although the above studies suggest Granulocyte-Colony Stimulating Factor is capable of mobilizing peripheral hematopoietic stem cells, it is not known if Granulocyte-Colony Stimulating Factor could induce the recruitment of either local or migration of peripheral stem cells to injured neural tissue, differentiate and restore neural function required for the slowly developing lesions found in most chronic diseases. Further, to our knowledge a “self-repair” system has not been described in human studies.
Diabetes is a major public health problem in the United States affecting 16 million people and accounts for one sixth of all health related expenditures. There are two types; Type 1 (insulin dependent diabetes) and Type 2 (noninsulin-dependent diabetes). Type 1 is characterized by beta cell loss and absolute insulin deficiency. Of the patients with diabetes today, approximately 90 to 95% of the inflicted are Type 2 diabetics. It is generally characterized by elevated fasting blood glucose and lack of sensitivity to insulin and impaired insulin secretion. The prevalence of Type 2 diabetes is about 7 percent for persons between 45 to 64 years of age. The microvascular and macrovascular complications of Type 2 diabetes causes significant morbidity and mortality in affected individuals. Diabetic retinopathy, neuropathy, and nephropathy are major causes of functional limitations and disability in this patient population. In the event that diet and exercise are not sufficient to control blood glucose, diabetics may be treated with one, and typically two, of several oral drugs able to lower blood glucose levels which include sulfonylureas, metformin, alpha-glucosidase, troglitazone, and repaglinide. These agents act on one of four mechanisms that alter renal function, liver metabolism, insulin secretion or breakdown of complex carbohydrates. If these drugs are insufficient, insulin treatment may be prescribed alone or together with these oral agents.
Improved glycemic control reduces the risk of microvascular complications in Type 2 diabetes. Despite this evidence, patients with Type 2 diabetes frequently do not maintain adequate glycemic control. However, the health outcomes of patients with Type 2 diabetes who are treated with insulin to control glycemia do much better than those that do not. Patients are encouraged to use intensive insulin treatment protocols to better control blood sugar but analysis of their outcomes indicate that it did not affect the quality of life of patients in the intensive insulin treatment nor did it have a significant protective effect against cardiovascular diseases. There is evidence that tight glycemic control will decrease the incidence of microvascular complications so patients should be encouraged to use insulin and oral hypoglycemic agents. However, it is difficult to make a convincing argument to patients that do not currently have severe symptoms of disease associated with their elevated blood sugar levels. There are no other forms of medical treatment to lower blood glucose to an acceptable range. The ideal drug for these patients is one where a single drug can be taken periodically that is able to control blood glucose levels over the course of a month or longer with reduced side affects.
It is unknown whether the chronic progressive neurodegenerative and non-neurodegenerative disorders could be treated effectively by mobilizing the “self-repair” mechanism of the host or even if that “self-repair” mechanism could be detected in patients with these disorders. Furthermore, Parkinson's disease in humans is a systemic disease with symptoms that indicate the PNS is an important target tissue of this disease. Surprisingly, this invention directly demonstrated for the first time in humans the potential action of Granulocyte-Colony Stimulating Factors, known to mobilize stem cells into the peripheral blood as well as to cause them to differentiate, to also be a therapy to reverse symptoms of an adult onset neurodegenerative disorder such as Parkinson's disease. In addition, it was even more surprising that Type 2 diabetes was found to be effectively controlled by periodically administering of Granulocyte-Colony Stimulating Factors offering a new approach and a revolutionary treatment for this disease. In both cases of adult onset disease, the patient receiving the drug was provided a long term reversal of all disease symptoms and this allowed him to live a more normal lifestyle. Also, the extended period of time between courses of GCSF might also result in a lower incidence of side effects from drug therapy.